1. Field of the Invention
This invention relates to a running gear for railway vehicles having at least six wheelsets, or pairs of wheels, whereby arrangements of three wheelsets can be connected by means of coupling and guide elements, in particular for longitudinal and lateral guidance, to a truck frame. The truck frames can each turn rotate, or pivot, in relation to a vehicle frame.
2. Background Information
One problem with the configuration described above is that the ability of railway vehicles having three-axle trucks to take curves is largely determined by the middle wheelsets of the trucks, and the middle wheelsets in known realizations tend to the inside of the curve in a small radius curve. A lateral force is generated between the inside wheel and the rail, which presses the wheelset toward the outside of the curve and, in connection with tapered wheel profiles, generates a moment of force opposite to the direction of rotation of the curve.
The force and moment, compared to a freewheeling of the middle wheelset, thereby cause an increase in the level of the wheel-rail forces on the terminal axles, that is, the two axles corresponding to the wheelsets other than the middle wheelset.
To improve the curve compliance of railway vehicles having three-axle trucks, known devices include running gear in which the middle wheelset of each truck is installed so that it has sufficient lateral play in relation to the truck frame. In this manner, the middle wheelset can essentially be freely adjusted when the vehicle enters a curve having a small radius of curvature, on account of the absence of restoring forces between the wheelset and the truck frame in the lateral direction. The curve compliance of such railway vehicles is thus similar to the behavior of railway vehicles having two-axle trucks and a wheelbase which corresponds to the distance between the two terminal axles of the three-axle trucks.
Such designs have the disadvantage that when the train is travelling through a curve with an excess of centrifugal force, the middle wheelset tends not to participate in the transmission of the centrifugal forces from the vehicle body and the truck frame to the rail, and thereby increases the proportion of such forces which must be transmitted by the terminal wheelsets of the trucks. This can lead to unacceptably high rail displacement forces, in particular when the vehicle travels through curves at high speeds.